Electronic seal is an important technology in nuclear disarmament verification, which is also widely used in nuclear safeguards, nuclear nonproliferation and other fields. This paper proposes a low vulnerability electronic fiber optic seal scheme according to the requirements of performance and low vulnerability for the seal. The seal system mainly consists of two major components, including the main control circuit and the secondary control circuit. The main control circuit includes the main microcontroller unit, the optical measuring unit, the temperature measuring unit, the switch measuring unit, the acceleration measuring unit and a data storage unit, mainly to complete multiple tamper indicating. In the main control circuit, the main microcontroller unit is the core of the system, mainly to implement the timing trigger, the timing adjustment, system fault diagnosis, fiber-optic monitoring, temperature monitoring, switch module monitoring, acceleration monitoring, and so on. The secondary control circuit includes a USB microcontroller unit and the encryption chip, mainly to complete data encryption and authentication. In the secondary control circuit, the USB microcontroller is mainly to implement the communication with external verification PC, legitimate users identification, encrypted-data transmission, starting/stopping the seal, clock synchronization calibration, and so on. In this way, the designed electronic fiber optic seal has been provided with multiple anti-tampering capabilities and lower vulnerability.

Most of the existing nuclear power plants locate in coastal mountainous region. In the traditional way, radio communication is used between the environmental radiation monitoring stations and monitoring center. As the terrain and thunderstorms have great impact on radio, the signal is easily disturbed or intercepted. At the same time, the technologies and functions of the conventional system is no able to fully meet the requirements of the environmental monitoring of nuclear power plant in new situation. A utility model of environmental radiation online monitoring system of nuclear power plants is put forward to solve the former problems. The system includes a monitoring center with capability of data processing and multiple monitoring stations with capability of environmental radiation online monitoring. Each of stations has radiation detectors as the monitoring center consists of a main server and a backup server. The communications between the monitoring center and Stations include wire communication and wireless communication. Wire communication mentioned above consists of public telephone network and telephone lines between the network and monitoring stations. The wireless communication mentioned above consists of public telecommunication service network and virtual private network (VPN) which is able to transfer data confidentially. Through the network, monitoring center uses two servers to provide wire and wireless data reception service. Monitoring stations choose one of the normal channels to transfer environmental radiation monitoring data. Based on the status of communication, data will be shared and synchronized automatically between the main server and backup server. On the basic of the architecture of equipment and network, some software systems are designed and developed. The main subsystems of the software systems are the data acquisition workstation software systems and the central station software system. These two kinds of subsystems play different role in system. Some new computer technology (such as Microsoft .Net, Geographic Information System) is used in these software systems to provide better functions which include data storage, data management, data show, statistics and analysis to enhance efficiency and reliability. In the practical application of some NPPs in China, the utility model solves the former problems of environmental radiation online monitoring effectively and makes the system more dependable. It can be transplanted and popularized in other coastal nuclear power plants.

The pebble bed modular reactor (PBMR) is a high temperature gas-cooled reactor which uses helium gas as a coolant. The PBMR design relies on the excellent heat transfer properties of graphite and a fuel design that is inherently resistant to the release of the radioactive material up to high temperatures. The safety characteristics of the PBMR concept are excellent. However, a very strong safety case will have to be made if a new generation of reactors is to be successfully introduced to a concerned public. Until recent developments in computational fluid dynamics methods, computer speed, and data storage, the coupled thermal-hydraulic, chemical, and mass transport phenomena could not be treated in an integrated analysis. This paper addresses one aspect of the interplay between the details of fluid flow and aerosol transport within the complex geometry of the pebble bed core. A very large quantity of graphite dust is produced by the interaction among the pebbles. The potential for the deposition of radionuclides on the surface of dust particles and their subsequent transport as aerosols is substantial. This effort focuses on the inertial deposition of these aerosols within the pebble bed. Inertial deposition in the low Reynolds number regime of laminar flow in pebble beds has been explored previously, but with less powerful computational techniques. Some experimental data are also available in this regime. No analyses or experimental data are available in the high Reynolds number turbulent regime in which the PBMR operates. This paper describes results of analyses of inertial deposition obtained with the FLUENT computational fluid dynamics code. The objective of the analysis is to obtain an expression for deposition within an asymptotic unit cell, removed from the boundary conditions at the entrance to the array. The results of analyses performed at different velocities and fluid densities in the turbulent regime were correlated against a modified Stokes number. The deposition correlation is well represented by the integral form of the normal distribution. Deposition for the time-averaged flow was found to be insensitive to the flow model. In the laminar regime, FLUENT results were found to be in agreement with earlier published results and experimental data. The stochastic behavior of eddies was also simulated within FLUENT using the k –ε model. Eddy-enhanced deposition results in greater deposition at all aerosol sizes in comparison with the time-averaged results, with significant deposition of aerosols predicted for small aerosol sizes. However, it is likely that these results are quite sensitive to the modeling of turbulence and they must be considered preliminary.